<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link rel="stylesheet" href="./style/index.css">
    <style>
        #leo {
            /*width: 100px;*/
            /*height: 100px;*/
            background: red;
        }

        #scan {
            width: 300px;
            height: 300px;
            background: #747bff;
        }
    </style>
</head>
<body style="background:orange">

<div id="leo">abc</div>
<div id="scan">123</div>
<div id="blue">hello</div>

</body>
</html>